title: Exhaust emissions of volatile organic compounds of powered two-wheelers: effect of cold start and vehicle speed. Contribution to greenhouse effect and tropospheric ozone formation.
abstract: Powered two-wheeler (PTW) vehicles complying with recent European type approval standards (stages Euro 2 and Euro 3) were tested on chassis dynamometer in order to measure exhaust emissions of about 25 volatile organic compounds (VOCs) in the range C1-C7, including carcinogenic compounds as benzene and 1,3-butadiene. The fleet consists of a moped (engine capacity ≤ 50 cm(3)) and three fuel injection motorcycles of different engine capacities (150, 300 and 400 cm(3)). Different driving conditions were tested (US FPT cycle, constant speed). Due to the poor control of the combustion and catalyst efficiency, moped is the highest pollutant emitter. In fact, fuel injection strategy and three way catalyst with lambda sensor are able to reduce VOC motorcycles' emission of about one order of magnitude with respect to moped. Cold start effect, that is crucial for the assessment of actual emission of PTWs in urban areas, was significant: 30-51% of extra emission for methane. In the investigated speed range, moped showed a significant maximum of VOC emission factor at minimum speed (10 km/h) and a slightly decreasing trend from 20 to 60 km/h; motorcycles showed on the average a less significant peak at 10 km/h, a minimum at 30-40 km/h and then an increasing trend with a maximum emission factor at 90 km/h. Carcinogenic VOCs show the same pattern of total VOCs. Ozone Formation Potential (OFP) was estimated by using Maximum Incremental Reactivity scale. The greatest contribution to tropospheric ozone formation comes from alkenes group which account for 50-80% to the total OFP. VOC contribution effect on greenhouse effect is negligible with respect to CO2 emitted.
authors.affiliation: Istituto Motori of National Council of Research, viale Marconi, 8, 80125 Naples, Italy. Electronic address: m.a.costagliola@im.cnr.it.
authors.forename: M Antonietta
authors.initials: MA
authors.lastname: Costagliola
authors.forename: Fabio
authors.initials: F
authors.lastname: Murena
authors.forename: M Vittoria
authors.initials: MV
authors.lastname: Prati
mesh_terms: D001272:Atmosphere / Q000737:chemistry*; D005062:European Union; D017752:Greenhouse Effect; D057230:Limit of Detection; D009049:Motorcycles / Q000592:standards*; D010126:Ozone / Q000032:analysis* / Q000737:chemistry; D001335:Vehicle Emissions / Q000032:analysis*; D055549:Volatile Organic Compounds / Q000032:analysis* / Q000737:chemistry
chemical_list: D001335:Vehicle Emissions; D055549:Volatile Organic Compounds; D010126:Ozone
keywords: Carcinogenic compounds; Cold start; Greenhouse effect; Ozone formation potential; Two-wheeler exhaust emissions; VOC